Annular magnetic powder core and preparation mold of annular magnetic powder core

Abstract

The invention relates to the technical field of magnetic powder cores, and provides an annular magnetic powder core and a preparation mold of the annular magnetic powder core. And the cross section of the annular magnetic powder core is circular. According to the annular magnetic powder core, the shape of the cross section of the annular magnetic powder core is set to be circular, the magnetic powder consumption during preparation of the annular magnetic powder core is reduced, the magnetic flux density of the annular magnetic powder core is improved, meanwhile, the consumption of copper wires is reduced during coil winding, and therefore the manufacturing cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic powder cores, and in particular to an annular magnetic powder core and a preparation mold for the annular magnetic powder core. Background Art

[0002] As a functional material, magnetic powder cores are increasingly widely used in power electronic equipment and devices. With the rapid development of the electronic power and information industries, lightweight, high frequency and high current have become development trends, requiring magnetic powder cores to have high saturation flux density, high magnetic permeability, low loss and good temperature stability.

[0003] The existing annular magnetic powder core has a rectangular cross-section, a low magnetic flux density, and a large amount of copper wire is used during winding, resulting in a high manufacturing cost. Summary of the invention

[0004] The invention provides an annular magnetic powder core and a preparation mold of the annular magnetic powder core, which are used to solve the defects of low magnetic flux density and high manufacturing cost of the annular magnetic powder core in the prior art.

[0005] The invention provides an annular magnetic powder core, the cross section of which is circular.

[0006] According to the annular magnetic powder core provided by the present invention, the magnetic flux density of the inner ring of the annular magnetic powder core is greater than the magnetic flux density of the outer ring.

[0007] According to the annular magnetic powder core provided by the present invention, the magnetic flux density of the inner ring of the annular magnetic powder core is 6.25 g / cm 3 -6.30 g / cm 3 The magnetic flux density of the outer ring of the annular magnetic powder core is 6.20 g / cm 3 -6.25 g / cm 3 .

[0008] According to the annular magnetic powder core provided by the present invention, the upper end and the lower end of the annular magnetic powder core retain an arc-shaped non-polished portion, and the width of the retained arc surface is 1 / 48 to 1 / 8 of the circumference of the circular cross-section.

[0009] The present invention also provides a mold for preparing the annular magnetic powder core as described above, wherein the mold cavity of the preparation mold is in the shape of a circular ring.

[0010] According to a preparation mold for an annular magnetic powder core provided by the present invention, the preparation mold comprises: an upper mold, a middle mold and a lower mold, the middle mold is stacked on the lower mold, the upper mold can be embedded in the middle mold, and the upper mold can cover the lower mold.

[0011] According to a preparation mold for an annular magnetic powder core provided by the present invention, the lower mold is provided with a first cavity, the upper mold is provided with a second cavity, the first cavity and the second cavity are both annular cavities, and the cross-sectional shape of the annular cavity is an arc shape; the middle mold has an annular cavity, the annular cavity is connected to the first cavity, the upper mold can move linearly along the annular cavity, and after the upper mold and the lower mold are covered, the first cavity and the second cavity form a circular ring.

[0012] According to a mold for preparing an annular magnetic powder core provided by the present invention, first flash grooves are arranged around the first cavity, second flash grooves are arranged around the second cavity, and the second flash grooves are opposite to and connected to the first flash grooves.

[0013] According to a mold for preparing an annular magnetic powder core provided by the present invention, the outer walls of the lower mold and the upper mold are respectively provided with a plurality of exhaust holes, and each of the exhaust holes is connected to the first cavity or the second cavity.

[0014] According to a mold for preparing an annular magnetic powder core provided by the present invention, the middle mold includes: a first mold ring and a second mold ring, the second mold ring is sleeved in the first mold ring, and the annular cavity is formed between the first mold ring and the second mold ring; the inner diameter of the first mold ring is equal to the diameter of the outer ring of the first cavity, and the outer diameter of the second mold ring is equal to the diameter of the inner ring of the first cavity.

[0015] The annular magnetic powder core provided by the present invention reduces the amount of magnetic powder used in the preparation of the annular magnetic powder core by setting the cross-sectional shape of the annular magnetic powder core to a circle, improves the magnetic flux density of the annular magnetic powder core, and at the same time, reduces the amount of copper wire used when winding the coil, thereby greatly reducing the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of a mold for preparing an annular magnetic powder core provided by the present invention.

[0018] Figure 2 It is a schematic diagram of the structure of the formed annular magnetic powder core and the target annular magnetic powder core.

[0019] Reference numerals: 1. Lower mold; 2. Middle mold; 3. Upper mold; 11. first cavity; 12. first flash groove; 21. first die ring; 22. second die ring; 31. second cavity; 32. second flash groove; 100, flash; 200, annular magnetic powder core. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0024] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0026] Combine the following Figure 1 and Figure 2 The invention discloses a toroidal magnetic powder core and a mold for preparing the toroidal magnetic powder core.

[0027] like Figure 2 As shown, in the embodiment of the present invention, the cross-sectional shape of the annular magnetic powder core is circular.

[0028] Specifically, in the prior art, the cross-sectional shape of the annular magnetic powder core is usually rectangular, and the annular magnetic powder core with a rectangular cross-sectional shape has disadvantages in terms of magnetic flux density, automated application, and copper wire cost during winding, while the annular magnetic powder core 200 with a circular cross-sectional shape has a higher magnetic flux density. When forming the annular magnetic powder core, less magnetic powder is required, thereby reducing the manufacturing cost; in addition, when winding the coil, for the same window area, the annular magnetic powder core 200 with a circular cross-sectional shape requires less copper wire, thereby further reducing the manufacturing cost.

[0029] The annular magnetic powder core provided in the embodiment of the present invention reduces the amount of magnetic powder used in the preparation of the annular magnetic powder core and improves the magnetic flux density of the annular magnetic powder core by setting the cross-sectional shape of the annular magnetic powder core to a circle. At the same time, when winding the coil, the amount of copper wire used is reduced, thereby greatly reducing the manufacturing cost.

[0030] In the embodiment of the present invention, the magnetic flux density of the inner ring of the annular magnetic powder core 200 is greater than the magnetic flux density of the outer ring.

[0031] Specifically, the preparation method of the annular magnetic powder core 200 is: placing magnetic powder in a mold, and the mold presses the magnetic powder into an annular structure. In this embodiment, the outer wall of the mold is provided with an exhaust hole, and the exhaust hole is connected to the mold cavity of the mold to prevent the gas in the mold from being unable to be discharged during the pressing process, resulting in stress concentration and damage to the mold. Since the exhaust hole is arranged close to the outer ring of the annular magnetic powder core 200, the magnetic flux density of the outer ring of the annular magnetic powder core 200 is less than the magnetic flux density of the inner ring.

[0032] In the embodiment of the present invention, the magnetic flux density of the inner ring of the annular magnetic powder core 200 is 6.25 g / cm 3 -6.30 g / cm 3 Optionally, in this embodiment, the magnetic flux density of the inner ring of the annular magnetic powder core 200 is 6.28 g / cm 3 .

[0033] In the embodiment of the present invention, the magnetic flux density of the outer ring of the annular magnetic powder core 200 is 6.20 g / cm 3 -6.25 g / cm 3 Optionally, in this embodiment, the magnetic flux density of the outer ring of the annular magnetic powder core 200 is 6.22 g / cm 3 .

[0034] The conventional annular magnetic powder core has a rectangular cross-section. The magnetic flux density of the inner ring is equal to that of the outer ring, both of which are 6.22 g / cm 3 The magnetic flux density of the inner ring of the annular magnetic powder core provided by the embodiment of the present invention is greater than 6.22 g / cm 3 Thus, the overall magnetic core performance of the annular magnetic powder core 200 is more excellent.

[0035] The annular magnetic powder core provided in the embodiment of the present invention designs the cross-sectional shape of the annular magnetic powder core to be circular, so that the inductor design can achieve the same magnetic core energy with a smaller volume, laying a solid foundation for the subsequent automation of inductor winding.

[0036] like Figure 1 As shown, an embodiment of the present invention further provides a mold for preparing an annular magnetic powder core, wherein the cavity of the preparation mold is in the shape of a circular ring.

[0037] The mold for preparing annular magnetic powder core provided in an embodiment of the present invention can manufacture annular magnetic powder core by designing the mold cavity into a circular ring shape; at the same time, by designing the mold cavity into a circular ring shape, the amount of magnetic powder required for forming the annular magnetic powder core is reduced, thereby reducing the manufacturing cost.

[0038] like Figure 1 As shown, in an embodiment of the present invention, the preparation mold includes: a lower mold 1, a middle mold 2 and an upper mold 3. The middle mold 2 is stacked on the lower mold 1, the upper mold 3 can be embedded in the middle mold 2, and the upper mold 3 can cover the lower mold 1.

[0039] Specifically, in this embodiment, the middle mold 2 is used to guide and position the upper mold 3 so that the upper mold 3 is aligned with the lower mold 1 to form a complete cavity to form the annular magnetic powder core 200.

[0040] like Figure 1 As shown, the lower mold 1 is provided with a first cavity 11, and the upper mold 3 is provided with a second cavity 31. The first cavity 11 and the second cavity 31 are both annular cavities, and the cross-sectional shape of the annular cavity is an arc shape. The middle mold 2 has an annular cavity, which is connected to the first cavity 11. The upper mold 3 can move linearly along the annular cavity. After the upper mold 3 and the lower mold 1 are covered, the first cavity 11 and the second cavity 31 form a circular ring.

[0041] Specifically, the lower die 1 is provided with an annular cavity, and the cross-sectional shape of the annular cavity is an arc shape. The upper die 3 is also provided with an annular cavity, and the annular cavity is symmetrically arranged with the annular cavity on the lower die 1. The middle die 2 is arranged on the lower die 1, and the annular cavity of the middle die 2 is aligned with and connected with the annular cavity of the lower die 1. When forming the annular magnetic powder core 200, the magnetic powder is placed in the annular cavity of the lower die 1 and the annular cavity of the middle die 2, and then the upper die 3 is embedded in the annular cavity, and pressure is applied to the upper die 3, and the upper die 3 and the lower die 1 are covered to squeeze the magnetic powder to form the annular magnetic powder core 200.

[0042] In this embodiment, the middle mold 2 can play a guiding and positioning role, so that the second cavity 31 of the upper mold 3 is exactly aligned with the first cavity 11 of the lower mold 1; at the same time, the middle mold 2 also plays a role in accommodating magnetic powder, so that the first cavity 11 and the annular cavity can accommodate a sufficient amount of magnetic powder to ensure that the annular magnetic powder core 200 after forming will not have local meat shortage.

[0043] In this embodiment, the diameter of the cavity formed by connecting the first cavity 11 and the second cavity 31 should be slightly larger than the diameter of the annular magnetic powder core 200. During the forming process, after the magnetic powder fills the cavity, the size of the annular magnetic powder core 200 after forming can be guaranteed to reach the target size.

[0044] The preparation mold for the annular magnetic powder core provided in the embodiment of the present invention can guide and position the upper mold by setting a middle mold, and at the same time, form a magnetic powder accommodating space to accommodate a target amount of magnetic powder, thereby ensuring that the size of the annular magnetic powder core after forming meets the target size.

[0045] like Figure 1As shown, in an embodiment of the present invention, the middle mold 2 includes: a first mold ring 21 and a second mold ring 22, the second mold ring 22 is sleeved in the first mold ring 21, and an annular cavity is formed between the first mold ring 21 and the second mold ring 22, and the first mold ring 21 and the second mold ring 22 are both arranged on the lower mold 1.

[0046] Specifically, in this embodiment, the first die ring 21 and the second die ring 22 are sleeved to form the middle die 2. The first die ring 21 and the second die ring 22 are two independent components. The inner diameter of the first die ring 21 is equal to the diameter of the outer ring of the first cavity 11, and the outer diameter of the second die ring 22 is equal to the diameter of the inner ring of the first cavity 11. When the first die ring 21 and the second die ring 22 are arranged on the lower die 1, the annular cavity formed between the first die ring 21 and the second die ring 22 is just aligned with and connected to the first cavity 11.

[0047] During the forming process of the annular magnetic powder core 200 , force is applied to the upper die 3 , and the upper die 3 moves downward to squeeze the magnetic powder, thereby pressing the magnetic powder into the annular magnetic powder core 200 .

[0048] like Figure 1 As shown, in the embodiment of the present invention, a first flash groove 12 is provided around the first cavity 11 , and a second flash groove 32 is provided around the second cavity 31 . The second flash groove 32 is opposite to and connected with the first flash groove 12 .

[0049] Specifically, in order to ensure that the size of the annular magnetic powder core 200 after pressing and forming meets the process requirements and there is no local lack of meat, in this embodiment, a first flash groove 12 is set around the first cavity 11, and a second flash groove 32 is set around the second cavity 31. During the pressing and forming process, the magnetic powder first fills the cavity, and the excess material is squeezed into the first flash groove 12 and the second flash groove 32 to form a flash 100, so that the size of the annular magnetic powder core 200 after forming can reach the target size.

[0050] like Figure 2 As shown, the outer ring and the inner ring of the formed annular magnetic powder core 200 both have obvious flash 100, and the flash 100 can be removed by grinding to make the annular magnetic powder core 200 into a circular ring structure.

[0051] The length from one burr edge of the annular magnetic powder core 200 to the other burr edge of the annular magnetic powder core 200 before grinding is ≥ the longitudinal length of the annular magnetic powder core 200; when the burr edge 100 is ground off, considering the need to ensure the specifications and shape of the annular magnetic powder core 200 and save materials, the grinding is performed based on the longitudinal direction of the cross section of the annular magnetic powder core 200 to ensure that the cross section of the annular magnetic powder core 200 is circular. Therefore, the upper and lower ends of the annular magnetic powder core 200 after grinding retain non-grinding parts, and the retained arc width is approximately 1 / 48 to 1 / 8 of the circumference of the circular cross section, preferably 1 / 16; the surface of the non-grinding part is smooth, and grinding marks are clearly visible on the polished part.

[0052] Furthermore, in the embodiment of the present invention, the outer walls of the lower mold 1 and the upper mold 3 are respectively provided with a plurality of exhaust holes, and each exhaust hole is communicated with the first cavity 11 or the second cavity 31 .

[0053] Specifically, the exhaust hole is used to exhaust the gas in the mold during the pressing process to prevent the stress concentration in the mold during the pressing process and damage the mold. Since the exhaust hole is arranged close to the outer ring of the annular magnetic powder core 200, the magnetic flux density of the outer ring of the annular magnetic powder core 200 is smaller than the magnetic flux density of the inner ring.

[0054] The following is a detailed description of the method for preparing the annular magnetic powder core provided by the embodiment of the present invention.

[0055] The annular magnetic powder core provided by the embodiment of the present invention is prepared from magnetic powder, and the magnetic powder is a mixture of sendust powder and iron silicon powder. The composition of the sendust powder is FeSiAl, wherein the mass ratio of Si is 8.0%-10.0%, preferably 8.8%; the mass ratio of Al is 4.5%-6.5%, preferably 5.26%, and the rest is Fe; the composition of the iron silicon powder is FeSi, wherein the mass ratio of Si is 4.5%-6.5%, preferably 5.5%, and the rest is Fe. The mass ratio of FeSiAl in the sendust powder and the iron silicon powder is 70%-90%, preferably 85%; the rest is FeSi.

[0056] Add the mixture to the mixed coating liquid, stir evenly, dry and sieve to form insulating powder. Add a demoulding lubricant to the insulating powder and mix evenly. The content of the demoulding lubricant is 0.2%~0.4%, preferably 0.35%. The insulating powder is quantitatively added to the cavity of the preparation mold through the press shoe, and the pressing pressure is 20-21 tons / square centimeter. After pressing and molding, the annular magnetic powder core 200 is subjected to stress relief annealing, the annealing temperature is 760-800℃, preferably 790℃, and the annealing time is 40-60min, preferably 50min. After heat treatment, the annular magnetic powder core 200 is impregnated, chamfered and coated to obtain the final product.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A toroidal magnetic powder core, characterized in that: The cross-section of the annular magnetic powder core is circular.

2. The annular magnetic powder core according to claim 1, characterized in that: The magnetic flux density of the inner ring of the annular magnetic powder core is greater than the magnetic flux density of the outer ring.

3. The annular magnetic powder core according to claim 2, characterized in that: The magnetic flux density of the inner ring of the annular magnetic powder core is 6.25g / cm 3 -6.30 g / cm 3 The magnetic flux density of the outer ring of the annular magnetic powder core is 6.20 g / cm 3 -6.25 g / cm 3 .

4. The annular magnetic powder core according to claim 1 or 2, characterized in that: The upper end and the lower end of the annular magnetic powder core both retain an arc-shaped non-polished portion, and the width of the retained arc surface is 1 / 48 to 1 / 8 of the circumference of the circular cross section.

5. A mold for preparing the annular magnetic powder core according to any one of claims 1 to 4, characterized in that: The cavity of the preparation mold is annular.

6. The mold for preparing the annular magnetic powder core according to claim 5, characterized in that: The preparation mold comprises: an upper mold, a middle mold and a lower mold, the middle mold is stacked on the lower mold, the upper mold can be embedded in the middle mold, and the upper mold can cover the lower mold.

7. The mold for preparing the annular magnetic powder core according to claim 6, characterized in that: The lower mold is provided with a first cavity, and the upper mold is provided with a second cavity, the first cavity and the second cavity are both annular cavities, and the cross-sectional shape of the annular cavity is an arc shape; The middle mold has an annular cavity, which is connected to the first cavity. The upper mold can move linearly along the annular cavity. After the upper mold and the lower mold are covered, the first cavity and the second cavity form a circular ring.

8. The mold for preparing the annular magnetic powder core according to claim 7, characterized in that: A first flash groove is arranged around the first cavity, and a second flash groove is arranged around the second cavity. The second flash groove is opposite to and connected with the first flash groove.

9. The mold for preparing annular magnetic powder core according to claim 7, characterized in that: The outer walls of the lower mold and the upper mold are respectively provided with a plurality of exhaust holes, and each of the exhaust holes is communicated with the first cavity or the second cavity.

10. The mold for preparing annular magnetic powder core according to claim 7, characterized in that: The middle mold comprises: a first mold ring and a second mold ring, the second mold ring is sleeved inside the first mold ring, and the annular cavity is formed between the first mold ring and the second mold ring; The inner diameter of the first die ring is equal to the diameter of the outer ring of the first cavity, and the outer diameter of the second die ring is equal to the diameter of the inner ring of the first cavity.

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